Custom marker in google maps in android with vector asset icon

You can use this method:

private BitmapDescriptor bitmapDescriptorFromVector(Context context, int vectorResId) {
        Drawable vectorDrawable = ContextCompat.getDrawable(context, vectorResId);
        vectorDrawable.setBounds(0, 0, vectorDrawable.getIntrinsicWidth(), vectorDrawable.getIntrinsicHeight());
        Bitmap bitmap = Bitmap.createBitmap(vectorDrawable.getIntrinsicWidth(), vectorDrawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        vectorDrawable.draw(canvas);
        return BitmapDescriptorFactory.fromBitmap(bitmap);
}

So your code will look like:

map.addMarker(new MarkerOptions()
                .position(latLng)
                .icon(bitmapDescriptorFromVector(getActivity(), R.drawable.your_vector_asset))
                .title(title);

Edit:
In Kotlin it may look like:

private fun bitmapDescriptorFromVector(context: Context, vectorResId: Int): BitmapDescriptor? {
        return ContextCompat.getDrawable(context, vectorResId)?.run {
            setBounds(0, 0, intrinsicWidth, intrinsicHeight)
            val bitmap = Bitmap.createBitmap(intrinsicWidth, intrinsicHeight, Bitmap.Config.ARGB_8888)
            draw(Canvas(bitmap))
            BitmapDescriptorFactory.fromBitmap(bitmap)
        }
    }

I was looking for exact same requirement, and seeing this question made me happy at first, but same as @Shuddh I wasn't happy with the given answers.

To make my story short, I am using following code for this requirement:

private BitmapDescriptor bitmapDescriptorFromVector(Context context, @DrawableRes  int vectorDrawableResourceId) {
    Drawable background = ContextCompat.getDrawable(context, R.drawable.ic_map_pin_filled_blue_48dp);
    background.setBounds(0, 0, background.getIntrinsicWidth(), background.getIntrinsicHeight());
    Drawable vectorDrawable = ContextCompat.getDrawable(context, vectorDrawableResourceId);
    vectorDrawable.setBounds(40, 20, vectorDrawable.getIntrinsicWidth() + 40, vectorDrawable.getIntrinsicHeight() + 20);
    Bitmap bitmap = Bitmap.createBitmap(background.getIntrinsicWidth(), background.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    background.draw(canvas);
    vectorDrawable.draw(canvas);
    return BitmapDescriptorFactory.fromBitmap(bitmap);
}

and a usage example:

.icon(bitmapDescriptorFromVector(this, R.drawable.ic_car_white_24dp));

Note: you may wish to use different bounding for your vectors, my vectors were 24dp in size and I've used a 48dp png image(blue-part, which can be a vector too) as background.

UPDATE: Adding screenshot as it was requested.

Here is the code for kotlin lovers ;)

private fun bitMapFromVector(vectorResID:Int):BitmapDescriptor {
    val vectorDrawable=ContextCompat.getDrawable(context!!,vectorResID)
    vectorDrawable!!.setBounds(0,0,vectorDrawable!!.intrinsicWidth,vectorDrawable.intrinsicHeight)
    val bitmap=Bitmap.createBitmap(vectorDrawable.intrinsicWidth,vectorDrawable.intrinsicHeight,Bitmap.Config.ARGB_8888)
    val canvas=Canvas(bitmap)
    vectorDrawable.draw(canvas)
    return BitmapDescriptorFactory.fromBitmap(bitmap)
}